Exercise Helps Protect Black Women From Breast Cancer, Study Says

They followed more than 44,000 black women for 16 years. They found those who exercised vigorously for seven or more hours a week were 25 percent less likely to develop breast cancer than those who worked out less than an hour a week.

The exercises included swimming, running, basketball and aerobics in addition to brisk walking. However, walking at a normal pace was not associated with a lower breast cancer risk.

"Although expert review panels have accepted a link between physical exercise and breast cancer incidence, most study participants have been white women. This is the first large-scale study to support that vigorous exercise may decrease incidence of breast cancer in African-American women," principal investigator Lynn Rosenberg, a professor of epidemiology at Boston University School of Public Health, said in a university news release.

The study was published online recently in the journal Cancer Epidemiology, Biomarkers & Prevention.